A content delivery network(CDN) is a system of distributed servers(network) that deliver web pages and other web content to a user based on the geographic locations of the user, the origin of the web page and content delivery server.

• Edge Location: This is the location where content will be cached. This is separate to an AWS Region/AZ.
• Origin: This is the origin of all the files that the CDN will distribute. This can be either an S3 Bucket, an EC2 Instance, an Elastic Load Balance or Route53.
• Distribution: This is the name given to the CDN which consists of a collection of Edge Locations.

Amazon CloudFront can be used to deliver your entire website, including dynamic, static, streaming, and interactive content using a global network of edge locations.

Requests for your content will automatically be routed to the nearest edge location, so content is delivered with the best possible performance.

Amazon CloudFront is optimized to work with other Amazon Web Service, like Amazon Simple Storage Service(S3), Amazon Elastic Compute Cloud(EC2), Amazon Elastic Load Balancing, and Amazon Route53.

Amazon CloudFront also works seamlessly with any non-AWS origin server, which stores the original, definitive versions of your files.

• Web Distribution: Typically used for Websites.
• RTMP: Used for media streaming.

這兩個都歸在 CDN Distribution 底下

• Edge locations are not READ only, you can write to them too(PUT an object to them), and objects will be replicated back to the original server.
• Objects are cached for the life of the TTL(Time to Live), we can set TTL on our object and that's how long it will be cached at edge locations.
• You can clear cached objects, but you will be charged.